Allow refactor/rename of accessors in compiler plugin

Sadly we cannot (yet) rename accessors using refactoring/renaming (Shift+F6).

Similarly, if you rename the source of a column name (so, a property in a `@DataSchema` interface/data class or a string literal) then any usage of the column accessor will simply turn red, instead of being renamed as well.

For the compiler plugin to really feel like part of the IDE it would be great to have this.

Start by reproducing the Shift+F6 cases described: renaming an accessor and renaming a @DataSchema property or string-literal column source. The issue names no files or tests, so first locate the compiler plugin's IDE refactoring entry points; done means accessor usages follow both kinds of source rename without becoming unresolved.

Written by the indexing model from the issue text.